What is a great driver for a beginning golfer that is very cost efficient?

There is no real "beginner" driver. So long as it's properly fit to you, almost ANY driver will be good for you. The only thing you have to look out for are those made with an aluminum face. Al doesn't have the same strength to elasticity ratio as titanium, so it has to be made thicker. That kills its Coefficient of Restitution rating. For a 90mph swing, it equates to about an 8 yard loss between the two metals, provided everything else is the same.

Another thing: don't be afraid of buying component brands, clones from reputable sources, or used name brands. Driver technology has been maxed out for 6 years now- if you're properly fitted, you'll be fine.

Look at companies like Hireko Golf, Diamond Tour Golf (they do both original stuff and clones), GigaGolf, GolfWorks, Golfsmith, Value Golf and Pinemeadow Golf. For the best results, look for a clubfitter in your area. Tell them your budget and they'll get you into your best- yet affordable- driver.